Vandals daubed Maen Llia standing stone in the Brecon Beacons National Park (Wales) with a smiley face. The 3.7m (12ft) stone is recognised as a site of national archaeological importance and it was erected in the Late Neolithic or Early Bronze Age between 2500 and 1800 BCE.
The graffiti is being removed from the stone which is situated between Heol Senni and Ystradfellte. Removal will be carried out between the national park authority, landowners and the Welsh government's historic environment service Cadw.
Natalie Ward, heritage officer for Brecon Beacons National Park Authority, said: "The person who did this may well think it was harmless fun but archaeological sites like Maen Llia are fragile and causing damage to a scheduled ancient monument is a criminal offence." Causing damage to a scheduled ancient monument is a criminal offence, and the graffiti at Maen Llia has been reported to Dyfed-Powys Police.